The aftermath of Typhoon Haiyan is turning critical. Those who survived are now facing other dangers and potentially life-threatening medical problems. At the top of that list is dehydration, which can trigger other diseases.

The once vibrant coastal city of Tacloban is now a wasteland covered in death, debris and destruction. Only a few buildings are left standing and bodies line the streets.

Doctors say humans can only survive four days without water. Now four days after the typhoon, most survivors still don't have shelter, food and, most importantly, clean water.

"A major cause of death in situations like this is diarrhea and dehydration. People don't have fresh water to drink. They don't have clean water to drink. They're desperate," said Dr. George Fallieras, hospitalist and emergency medicine specialist with Good Samaritan Hospital.

Fallieras provided medical care in the aftermath of Katrina and the 2010 Haiti Earthquake. He says many more people die in the days and weeks following the initial disaster. Following concerns of dehydration is often disease.

"Of course, the E. coli...people can also get typhoid, and there can also be cholera outbreaks," said Fallieras. "When there's all this standing water, all these people crowded, unsanitary conditions, you start to get the mosquito borne illnesses. People are at risk of getting malaria. People are at risk of getting dengue fever."

Relief workers know what the immediate needs are, but Fallieras says the only way to get water, tents, food and medical supplies to Filipino survivors is to support aid organizations who know how to get it there.

"You're not contributing maybe in a capacity that you want to by just providing money, but in situations like this, money is really what is the most necessary thing for these organizations," said Fallieras.